Important agreement between the French and Vietnamese nationalists that, had it been effectively implemented, would most likely have prevented the Indochina War (1946–1954). The agreement was signed in Hanoi on 6 March 1946 by Democratic Republic of Vietnam (DRV, North Vietnam) President Ho Chi Minh and Viet Nam Quoc Dan Dang (VNQDD, Vietnam National Party) leader Vo Hong Khanh for the Vietnamese and French diplomat Jean Sainteny for France to set the future relationship between North Vietnam and France.

Abandoned by both the United States and the Soviet Union and under pressure from China at the end of World War II, the North Vietnamese leadership now reluctantly agreed to a French military presence in North Vietnam. France was allowed to introduce 15,000 French and 10,000 Vietnamese troops under unified French command (the first French troops returned to Hanoi on 16 March) to protect French lives and property, but France promised to withdraw 3,000 of them each year. The agreement called for all of them to be gone by the end of 1951, with the possible exception of those guarding bases.

In return, France agreed to recognize the North Vietnamese government, which it had thus far refused to do. North Vietnam was to be a "free state with its own government, parliament, army and finances, forming part of the Indo-Chinese Federation of the French Union." In a key provision, France also agreed to the holding of a plebiscite in southern Vietnam to see whether it wanted to join North Vietnam in a unified state; however, no date for the vote was specified.

France also agreed to train and equip units of the new Vietnamese Army. In April general staff accords were signed by Generals Vo Nguyen Giap for North Vietnam and Raoul Salan for France, setting the location and size of troop garrisons.

The Ho-Sainteny Agreement, although much less than the Viet Minh wanted, was a framework that might have led to a working and positive relationship between France and North Vietnam had it been allowed to stand. The agreement was undermined, however, by French High Commissioner Georges Thierry d'Argenlieu's proclamation in Saigon on 2 June 1946 of the Republic of Cochin China, announced just after Ho Chi Minh's departure for Paris to negotiate with the French government on issues to implement the agreement. With an independent Republic of Cochin China, there would be no need for a plebiscite in southern Vietnam. D'Argenlieu's pronouncement and the intransigence of French negotiators in the ensuing Fontainebleau Conference helped produce the Vietnamese nationalist frustration that led to bloodshed and the beginning of the war that December.